1. Field of the Invention
The invention relates to fiber optical rotary joints and a fiber optic collimators particularly for use in optical rotary joints.
2. Description of Related Art
Various fiber optical rotary joints are known for transmission of optical signals between units that are rotatable relative to each other.
U.S. Pat. No. 5,371,814 discloses an optical rotary joint for a plurality of channels, having a Dove prism. An arrangement having a plurality of GRIN lenses is provided for coupling light into or out of glass fibers. Beam coupling or decoupling is performed by several separate lenses. The optical fibers attached to the lenses are held by means of ferrules.
U.S. Pat. No. 5,442,721 discloses another optical rotary joint having bundled collimators assemblies. These allow a further decrease in size and increase in optical quality. Here also the optical fibers attached to the lenses are held by means of ferrules.
U.S. Pat. No. 7,246,949 B2 discloses a rotary joint using a micro lens array. Fibers are held by a lens system block which is also part of the micro lens system. Here no further fiber support is disclosed.
US Patent Application Publication 2003/0142923 A1 discloses a fiber optic array where the fibers are attached by epoxy to the ferrules and further to the array housing. This causes cracks and degradation of the optical fiber when temperature changes abruptly or very high or low temperatures are applied.
A smaller part of the losses can be caused by thermally induced micro- and macrobending of the fibre which can be reduced by using a “Bending Loss Insensitive Single Mode Optical Fibre” as is disclosed in U.S. Pat. No. 7,440,663 or U.S. Pat. No. 7,623,747.